Washington ? Targeting Iran’s economy, the U.S. ordered tough new penalties Monday to further pinch the country’s financial system and encourage Israel to give sanctions more time before any military action against Iran’s nuclear program.

The new, stricter sanctions, authorized in legislation that President Barack Obama signed in December, will be enforced under an order he signed only now. They give U.S. banks new powers to freeze assets linked to the Iranian government and close loopholes that officials say Iran has used to move money despite earlier restrictions imposed by the U.S. and Europe.

The action against the Central Bank of Iran is more significant for its timing than its immediate effect. It comes as the United States and its allies are arguing that tough sanctions can still persuade Iran to back off what the West contends is a drive to build a nuclear bomb.

The U.S. and Europe want to deprive Iran of the oil income it needs to run its government and pay for the nuclear program. But many experts believe Iran will be able to find other buyers outside Europe.

The European Union announced last month it would ban the import of Iranian crude oil starting in July. The U.S. doesn’t buy Iranian oil but last month it placed sanctions on Iran’s banks to make it harder for the nation to sell crude. The U.S., however, has delayed implementing those sanctions for at least six months because it is worried about sending oil prices higher.